1. Field of the Invention
This invention concerns a special purpose hatch lid, or cover, that is adapted for use in gas freeing large tanks. It is especially applicable to tanks which contain fumes such as from hydrocarbons or the like.
In connection with large stock tanks, the periodic cleaning of the interior thereof involves entry within a tank by personnel. Consequently, there is the necessity of removing any fumes left over from the product which the tank contained.
2. Description of the Prior Art
It has been the practice heretofore to open any so-called thief hatches that are located in or near the top of a large tank, followed by the opening of a clean-out hatch located near the bottom of the tank. Then, personnel would enter through the clean-out hatch to proceed with a cleaning procedure. When that procedure was used for cleaning such tanks, it was necessary to allow a substantial amount of time to pass, e.g. on the order of many hours, for the fumes within the tank to exit through the thief hatch or hatches. However, by making use of a special hatch lid in accordance with this invention, the removal of fumes may be carried out in short order by connecting an eductor or other suction arrangement onto the latch lid while maintaining a tight seal for the fumes. Then, fumes are drawn out from the large tank.